package main

import "fmt"

func main() {
	//map、slice类型变量初始值为nil，添加元素时必须先初始化
	//读取，append时进行nil判断不需初始化
	//var course = map[string]string{}
	var course = make(map[string]string)

	// //var course map[string]string
	// //course["name"] = "math"
	fmt.Println(course["desc"])
}
